Research on collaborative cognition addresses the question of how social partners can enhance, or interfere with, one's thinking and problem solving. The current proposal explores how collaborative partners, particularly spouses, might enhance or interfere with older adults problem solving with familiar and relevant everyday problems. Several theoreticians have suggested that the availability of potential collaborators can be a critical component of successful cognitive performance in the everyday world. Consequently, in this study, a sample of 100 married couples (N=200), with both members of the dyad aged 60 years and older, will be randomly assigned to one of two conditions. In the married dyad condition, participants will work collaboratively with their spouse (N=50 couples). In the unacquainted dyad condition, participants will work with a married stranger of the opposite sex. Participants will work collaboratively on both instrumental (e.g., completing tax forms) and social (e.g., resolving a conflict with a family member) everyday problem-solving tasks. In addition, all participants will independently complete the same problem solving measures, as well as a battery of intellectual, personality, attitudinal, and relationship perception measures. The proposed study extends previous research on collaborative cognition in later adulthood by exploring a broader range of problem solving tasks, with higher everyday relevance, than has been studied in previous research. In addition, the study will explore several potential predictors of effective collaborations, as well as those specific interactive behaviors among collaborating dyads which are most facilitative of high dyadic problem-solving performance. Thus, the specific aims of the study are: (1) To investigate whether older adults endorse collaboration in their everyday tasks, and whether their attitudes toward collaboration vary by nature of the everyday task. (2) To examine the influence of a collaborative situation on the everyday problem solving of adults. (3) To determine how married collaborative partners differ from unfamiliar collaborators (e.g., randomly assigned gender-mixed pairs) in their dyadic solution of everyday problems. (4) To investigate how collaboration differs between instrumental and social problem-solving situations. (5) To explore how collaborative attitudes, dispositional characteristics (e.g., locus of control, gender identity), individual ability levels, and partner perception variables influence collaborative process and outcomes.